Sale 1:

https://backpack.tf/profiles/76561198002757046#!/compare/1528243200/1528329600

https://backpack.tf/profiles/76561198041408260#!/compare/1527984000/1528329600

May have sold for Rack? Calling outlier/untrace, may have been more in deal.

Sale 2:

https://backpack.tf/profiles/76561198041408260#!/compare/1529625600/1530576000

https://backpack.tf/profiles/76561198192602363#!/compare/1529712000/1529884800

Sold for Eldritch Hellmet(26.5)

Sale 3:

https://backpack.tf/profiles/76561198192602363#!/compare/1530576000/1530662400

https://backpack.tf/profiles/76561198241622178#!/compare/1530489600/1530662400

Sold for CH Gatsby

Gatsby Mini:

https://backpack.tf/profiles/76561198175420885#!/compare/1528761600/1528848000

https://backpack.tf/profiles/76561198304009353#!/compare/1528761600/1528848000

Sold for 28 keys

https://backpack.tf/profiles/76561198336395929#!/compare/1528675200/1528848000

https://backpack.tf/profiles/76561198175420885#!/compare/1528761600/1528848000

Sold for 27 keys

Taking 27-28 keys.

Total is 27.5 keys.

Sale 4:

https://backpack.tf/profiles/76561198241622178#!/compare/1530662400/1530748800

https://backpack.tf/profiles/76561198101185527#!/compare/1530748800/1530835200

Sold for CH Ushanka

Better used there.

Sale 5:

https://backpack.tf/profiles/76561198061248329#!/compare/1526515200/1526601600

https://backpack.tf/profiles/76561198054740469#!/compare/1526515200/1526601600

Better used there.

Sale 6:

https://backpack.tf/profiles/76561198054740469#!/compare/1526947200/1527120000

https://backpack.tf/profiles/76561198439478832#!/compare/1527033600/1527120000

Sold with 2 keys for G Fetti BoA(63)

Total is 61 keys.

Sale 7:

https://backpack.tf/profiles/76561198439478832#!/compare/1527033600/1527120000

https://backpack.tf/profiles/76561198089253101#!/compare/1527206400/1527292800

Sold for 28 keys + 14 ref

Sale 8:

https://backpack.tf/profiles/76561198089253101#!/compare/1527638400/1527724800

https://backpack.tf/profiles/76561198117332374#!/compare/1527552000/1527638400

Using there.

Sale 9:

https://backpack.tf/profiles/76561198117332374#!/compare/1528070400/1528416000

https://backpack.tf/profiles/76561198181288034#!/compare/1528329600/1528416000

Sold for N&B KE + 3 keys

KE Mini:

https://backpack.tf/profiles/76561198147900643#!/compare/1528588800/1528675200

Sold with 3 keys for DBD Titanium Pillar(27)

Taking 24 keys.

Sale 10:

https://backpack.tf/profiles/76561198181288034#!/compare/1528416000/1528502400

QS.

Sale 11:

https://backpack.tf/profiles/76561198002757046#!/compare/1530921600/1531008000

https://backpack.tf/profiles/76561198292137994#!/compare/1530748800/1530921600

Sold for 36 keys(keys came from item sales)

Sale 12:

https://backpack.tf/profiles/76561198292137994#!/compare/1530921600/1531094400

https://backpack.tf/profiles/76561198172573626#!/compare/1530921600/1531008000

Bulk.

Sale 13:

https://backpack.tf/profiles/76561198175015386#!/compare/1529107200/1529193600

https://marketplace.tf/items/15006;15;u703;w3;pk6

Sold for 70 USD

Total is ~36 keys.

Total sales @:

24, 26.5, 27.5, 28.4, 36, 36, 61

Going with 27 - 36 keys. 61 as an obvious outlier, keeping 36 due to 2 sales(1 pure one), and calling 24 a outlier due to difference from 26.5, and that KE might be inaccurate, due to having only one sale.